1. Field of the Invention
The present invention relates to a method for the preparation of reconstituted tobacco, aromatized by fermentation, to aromatized reconstituted tobaccos obtained by this method and to mixtures of tobaccos containing them.
During cigarette manufacture, only a part of the tobacco leaf, the lamina, is used. The midbribs (or stems) are removed by beating or stripping. The leaf is then chopped into shreds (orscaferlatis). These treatments give rise to fragments called fines, fragments or "scraps" and stems depending on their size and their origin. They represent up to 20% of the initial mass of tobacco and may be recycled and reintroduced into cigarettes, in the form of reconstituted tobacco.
The reconstitution consists in converting these fragments into a sheet which is later chopped and reincorporated into tobacco mixtures for cigarettes or used as the wrapping for cigars (binders and wrappers).
This sheet may be obtained by grinding, attrition or disaggregation of the fragments and then mixing with a binder and various additives (reinforcing fibers, fungicides, humectants, aromas and various fillers), spreading the paste obtained on an endless metal belt, drying, winding and, where appropriate, dividing the leaf into strips.
Many methods for reconstitution are known, for example, stratification methods, solvent evaporation methods, impregnation methods or extrusion methods. The reconstituted tobacco resulting from the first four methods is generally used for preparing the binders and wrappers for cigars.
For the production of sheets intended for use in tobacco mixtures for cigarettes, a paper-manufacturing method is most frequently used for reconstituting the tobacco, a typical diagram of which is given in FIG. 1. According to such a method, tobacco fragments originating from the beating or the chopping of the leaves are collected together and after sieving, mixed with water, for example in a digester 1, which enables the water-soluble products to be extracted. The soluble products are then separated from the insolubles, for example, by passing the paste obtained through a screw press 2. In such a paper method, the insoluble products are therefore separated from the soluble products so as to treat them separately. The fibers pass, for example, through a refiner 3 before passing through a papermaking machine 4 so as to form a sheet of tobacco fibers or the base sheet.
Soluble products in aqueous solution originating from the pressing, i.e. the strong liquor, are concentrated, for example, in a vacuum evaporating device 5, before being reincorporated into the base sheet so as to form a reconstituted sheet. The reconstituted sheet is then treated in a drying device 6.
Their reconstituted tobacco sheet will then be cut into thin sheets similar to tobacco strips which are reintroduced into tobacco mixtures for cigarettes.
In order to aromatize a tobacco, "sauces" or "tobacco juices" are usually introduced during manufacture.
These sauces may contain humectants such as glycerin or propylene glycol, sugars such as glucose or invert sugar, aromatizing agents such as cocoa, liquorice or fruit extracts, or synthetic aromatizing agents or additives.
In some conventional methods, the aromatization is carried out, for example, by spraying the "sauces" before or after drying the tobacco. In a reconstituted tobacco manufacturing method, these sauces or juices are added into the impregnation liquor. The major disadvantage of these sauces or juices stems from the fact that substances foreign to tobacco, and therefore the taste properties or "notes" which are not identical to those of tobacco, are introduced into the tobacco.
2. Description of the Prior Art
In another known aromatization method described in the publication FR-A-2,354,716 (which corresponds especially to publications GB 1,520,234, Au 2,353,977, U.S. Pat. No. 4,135,521, JP 52,156,999 and CA 1,074,986), an aromatization liquor which was obtained by fermenting a tobacco suspension to which a high proportion of sugar (20 kg of sugar per 10 kg of tobacco) was added and the suspension was filtered after fermentation and the filtered suspension was concentrated, if required, is introduced into the tobacco.
Application of this technique to the aromatization of a reconstituted tobacco sheet would therefore consist in adding to the said strong liquor defined above an aromatizing liquor, which will not be of any type, but would have been prepared in accordance with the teachings of the publication FR-A-2,354,716.
Such an aromatization method does not give satisfactory results either from a technical standpoint or from a profitability standpoint.